Method of and apparatus for removing free moisture from substances



Dec; 7 1926. 1,609,933

- G. H. ELMORE ET AL METHOD OF AND APPARATUS FOR REMOVING FREE MOISTURE FROM SUBSTANCES Filed August 24, 1923, 2 Sheets-Sheet 1 firm new Dec. 7 1926. V

G. H. ELMORE ETAL METHOD OF AND APPARATUS FOR REMOVING FREE MOISTURE FROM SUBSTANCES 2 Sheets-Sheet 2 Filed August 24 v gvwenfowz Guy /7. f/more, Ray C. Com/g4 Patented Dec; 7, 1926.

um'rso STATES,

PATENT orries;

GUY H. ELMORE AND BOY o. courier, or swan'rnmonn, rnnnsvnvanm.

METHOD OF AND APPARATUS FOR REMOVING FREE MOISTURE FBOM SUBS TANCES.

Application filed August 24, 1923. Serial no. 659,186

drier by which, under conditionslater ex plained, a preliminary drying is effected. The essential novelty or underlying principle of the invention resides in discharglng the treated matter by centrifugal force in a spreading or cone-like sheet or curtain, and causing the same to travel such distance before encountering any fixed surface or body that its free moisture, or all but a negligible portion thereof, is dissipated or taken up through congelation, through evaporation, or through the two processes jointly acting.

It is also advantageous, particularly where available space is limited or circumscribed, to cause the material treated to meet the fixed receiving surface at such angle as to insure a gliding of the material over the same, with a minimum of impact, for the reason that sharp impact tends to arrest crystallization when in progress or incomplete.

Prior to our present invention or discovery it has been customary to construct centrifugal driers with an encompassing shell or casing conforming as closely aspracticable to' therotor or rotary screen of the machine, in order to render the same compact and economical 1n construction. As a .consequence, the solid particles leaving the rotor'of the centrifugal drier and moving at high velocity, come almost immediately into contact with the interior surface of the shell or casing, making sharp impact thereon. It

close to the point at which the' material leaves the rotor, free moisture or liquid trickles down such surface In a stream which is contlnuous or practically so.

the like, which crystallize by the wet'way, surface moisture present on the granules or.

in the solution in process of-congelation or crystallization, will disappear if travel through the air be suificiently prolonged between the point of leaving the rotor and the first point of impact of the material-with any arresting body or surface. If on the other hand such travel be short, and the impact at all sharp or well defined, the free moisture is deposited upon the arresting surface, and is restored to 'andpassesolf with the f solid particles, thus neutralizing in greater or less measure the separationor drying already effected.

The disappearance of the moisture during prolonged-travel of the treated material, and which is nearly total, is apparently due in part to evaporation while said material is moving rapidly through the air or through the surrounding medium, and particularly to rapid congelation or crystallization, such liquid as remains free after passage of the material through the rotorbeing'ordinarilyin the form of a saturated or supersaturated solution, and hence readily crystallizable.

Accordingly, in carrying out our process. the delivery skirt of the rotor, is placed at a sufiicient height above the receiving bed" or platform, and the surrounding .wall or as closure is made ofsuch radius,-'as to permit an extended travel of the discharged material before coming into contact with said bed or platform, or with the encompassing It is hence obvlous that if these con 00 tion be given the material escaping from the rotor so that it will rise above the of discharge and then fall to the receiving wall. ditions be provided, or' if an upward direcintf platform, any convenient or suitable form of centrifugal drier may be utilized to carry out the process. The centrifugal type of drier is peculiarly advantageous in erforinmg the work, for the reason that t e particles leaving the rotor are'thro'wn ofi' atv ta'ng'ents to its skirt, and, are thereby sepa-" rated one from another, so that they are exposed on all sides to the air or other medium through which they travel in passing from the rotor to the receiving bed or platform.

It is further advantageous in that the solid material from which moisture is removed in its passage through the centrifugal drier, is propelled through the air without any expenditure of force additional to that required to effect the ordinary functions of the drier and without any rehandling after the centrifugal drier has performed its work of extracting moisture. For these reasons a centrifugal drier is the logical instrumentality to employ for projecting the partially dried material through the air. to effect the final drying, but it is not essential to the carrying out of the-present invention that a centrifugal drier be used for this purpose; it is sufficient that a rapidly moving rotor of some kind be employed to "throw ofl the product tangentially after the bulk of its moisture is removed, or after it .has parted with practically all the moisture removable by the means ordinarily employed for such purpose- Having thus explained the essentlal principle of our invention or discovery, we may briefly describe .apparatus suitable to carrying out the same, and illustrated in the ac companying drawings in which: I

Figure 1 shows partly in elevation and partly in section,a centrifugal drier with a rotary horizontal-bed or platform and an encircling or encompassing wall at such distance from the rotor of the drier as to permit evaporation, congelation, or evaporation and congelation, of moisture during the passage of the material from said rotor to the receiving bed;

Figure 2 is a top or plan view of the machine with one-half its upper casing removed to show the receiving bed and the fixed guard or skirt by which the deposited material is caused to move toward the circumference of the bed and to be discharged therefrom;

Figure 3 is a detail view of the roll and track gearing by which the receiving bed or platform is supported and rotated; and

Figure 4 is a detail view of a slight modification of the rotor.

The specific construction of the centrifugal drier employed is unimportant, and the invention ,ma be carried out with various types of 1 machines. I have, however, for convenience of illustration, shown a centrifugal machine well adapted to carryin out the work herein contemplated, which will be described sufiicientl' to make clear its general features and mo e of operatlon.

In the drawings, 1 indicates a substantial base or foundation which may be of cement construction or other, as found expedient in any given situation. Supported upon this foundation is a casing or enclosure 2 within which is contained the gearing by which the central solid shaft 3 and its encompassing tubular shaft or quill 4are driven at slightly differentspeeds but usually, and preferably, in the same direction. The central shaft 3 carries at its upper end an imperforate conical rotor 5 provided with a top section 6 in the form of a flattened cone, having on its upper face upstanding ribs or vanes 7 to distribute the inflowing material and deliver it into the annular space between the circumference of the rotor 5 and the inner wall of a second conical rotor 8. Both rotors are 7' concentric and of hollow form.

To prevent the lodging of material under treatment in said annular space, and to insure a proper downward travel thereof, blades 9 are secured to the circumference of the rotor 5, preferably in planes more or less oblique to that of the axis of the shafts 3 and 4. Suitable bearings for both shafts 3 and 4, preferably of the roller type, are provided in the lower part of the shell or casing 2, and atits top or in a substantial top settion 10 thereof. Those'at the top are seen in Fig, 1.

The tubular shaft or quill 4 carried at its upper end a head or'casting 11, which serves to cover or house the upper bearings of shafts 3 and 4, and has radial arms .or brackets 12 to support the outer rotor 8, the lower edge or skirt of which is' formed with a horizontal flange 13 which rests upon and is bolted to said arms or brackets. The conical circumference of rotor-8 is furnished with perforations, slits, or openings of any convenient form through which the moisture or' liquid separated from the body under treatment may escape. his usual and de-;

sharply inward from a oint above the slits or perforations in its wal but is formed with a quite large central opening concentric wlth ts axis of rotation, to receive the lower end of a feed spout 14 through whichis introduccd the material to be treated.

15 indicates an annular trough or launder supported by or suspended from a frame, in

turn carried by-an enclosing wall 16 which encompasses the centrifugal separator and its driving gear, said trough servin to receive -and carry away througha suita le outlet the liquid expelled from the material under treatment. Bolted or otherwise secured :to this launder l5 and encompassing the rotors is a shell or casing 17, which serves both toarrest the liquid thrown off by the rotorand direct it into the trough or launder, and to support the feed spout 14. The enclosing wall16, which may bemade of any as 'a-- carrier for this escaping material moves outward in a nearly horizontal sheet or curtaiznindividual particles of course moving on lines tangential to the circumference of "the rotors. Gravity causes a gradual descent or downward movement of the discharged matter, and the sheet or curtain of material consequently takes approximately the form of a flattened cone, or more accurately, a slightly concave-convex form. As the particles are. discharged tangentially from the rotor and once free therefrom preserve their lines of movement, they reach the inner face of wall 16 at a more or less actuate angle, and have a tendency to glide over the surface with which they contact- This is desirable since it reduces-the impact as compared with that incident to being, thrown squarely against the-arresting surface, or meeting it on a line perpendicular thereto.

Within the enclosing wall 16 is a rotary annular bed or platform 18, which receives the solid or treated matter discharged at the skirt of the rotor. This bed or platform 18 is provided on its under surface with an annular track-plate 19 having gear teeth 20 to mesh with the teeth 21 of conical gears 22, the teeth of the plate and gears being shrouded tothe pitch line, as seen in Fig. 1, so-that the shrouds form smooth contacting surfaces affording easy and regular travel of the bed or platform 18 when turned by rotation of the gears. (See Fig. 3.) One of the gears 22 is made fast to a shaft 23 carried in s litable bearings, and is provided with a wheel 24 of any suitable .character through which to receive rotary motion from any suitable rimemover, a sprocket wheel being here in icated.

()verlying and close to the surface of the bed or platform 18 is a curved guard or defiect-or 25 (Fig. 2),carriedat its inner end on a bracket or support 26 projecting from the casing 2, and supported at its outer end by the enclosing wall 16 through which is formed an opening 27 for escape of the material guided to said opening by guard 25 and advanced thereto by the rotation of the bed or platform. To prevent the material deposited on the bed or platform 18 from working off at either its lnner or its outer boundary, there is provlded a conical guard 28 carried by the central casing 2 and overhanging the inner edge or boundary of the bed or platform, and a second guard 29 made fast to the wall 16 similarly overhangs its outer edge. Both guards extend into close proximity to the upper face of the bed or platform 18.

In Fig. 4 there is illustrated a construction whereby an upward direction may be imparted to the material discharged by the rotors. This consists simply of a pair of annular extension sections 30, 31, of the outer walls of the rotors 5 and 8,'the sections being carried by the arms or brackets 12 of head 11, and hence rotating with said head and with the rotor 8 carried thereby. These wsec-tions.may conveniently be made of sheet T1 or plate metal of proper thickness, and are of truncated form, with their lower edges or skirts turned outward and slightly upward, so that the escaping material is given a slightly upward direction on leaving said extensions. This causes a longer travel of the material within a given radius than is obtainable where the material i directed somewhat downward or below the horizontal plane, in leaving the rotor. Obviously, the same result may be attained in other ways, as for instance, through'the use of a centrifugal machine employing conical rotors, but arranged with their bases or larger ends upward, and discharging at their upper ends. The present invention is concerned primarily with the broad idea of, or with embodying in working apparatus the principle of, so discharging the material after treatment by the centrifugal drier as to insure sufficient free travel through the air or surrounding medium to effect congelation, crystallization, or setting of free moisture carried by the granules, crystals or particles formed or forming at the time of discharge from the rotors.

Treatment of the fllIlO! surrounding mediumin which the centrifugal machine operates, to keep it dry and to enable it better to take up and carry off the free moisture on the particles of matter discharged from the rotor and during their travel through such medium, is contemplated but will not be described herein, the present a plication being confined to the broad idea 0 causing a relatively prolonged travel of the particles escaping from the rotor before they contact with 'any arresting surface, and to means generally for. effecting this result.

When employed for extracting mo sture from brine or other liquid or'semi-liquid yehicle,.or for treating other substanceswhlch might attack iron or steel, the rotors, lIIIIDgS, and the like, may be made of or plated or covered with brass, bronze, or.other noncorrodible material, or material but sllghtly affected by the substances treated.

The term congelation is herein used comprehensively ting, or hardening in the form of separated particles, whether this be due to evaporation, crystallization, chemical action, or other.

t is impracticable to .give specific dimensions of the apparatus, became these may vary according to the material and the condition of the material treated, the condition ofthe atmosphere or of the surrounding me diumin which the operation is performed, the direction of discharge of the material, the speed of the rotor and consequent velocity of the discharged particles, and similar considerations. The proportions indicated in the drawings have given good results in the treatment of substances which crystallize "by the wet way.

. The upward discharge is advantageous in that the necessary travel of the material can thereby be effected within an enclosure or space of somewhat smaller radius than where the discharge is approximately horizontal, or on a somewhat downward curve. Details of the apparatus may be varied as circumstances require or as experience shall sugest.

g The degree of dryness obtainable by the method'of treatment above set forth Varies somewhat according to the substance treated, its nature, and its condition when the treatment begins,-whether the surface of the particles be absorbent or non-absorbent, rough or smooth. In practice we have found that with crystalline substances, or sub stances of fairly smooth and non-absorbent surface, the moisture content can be reduced from 30% or thereabout as the material enters the machine to form 2% or 4 or 5% as it is finally delivered upon the receiving bed or platform. This applies to matter of about the coarseness of common salt and upward. YVith very fine crystals, such as' those of bicarbonate of soda, the moisture left in the crystals may be as low as 4 or 5%,but with the coarsermateri'als it is usually between 2 and 2%%. In the case of deliquescent substances, it is of course advisable to remove the material as speedily' as possible from the receiving'platforin, and place it under conditions which will guard against its breaking down.

What weclaim is 1. The method of eliminating free moisture from substances in a state of more or less nearly complete congelation or crystaL lization, which consists in subjecting the same to the action of a centrifugal drier; and cansing the treated material on leaving the rotor of such drier to travel through the air or surrounding medium free from'contact with any material support a distance sufficient to effect complete or partial dissipation of thefree moisture carried by the substance, through congelation, evaporation, or conjoint evaporation and congelation.

2. The process of eliminating free moisture from substances in a state of more or less nearly complete congelation or crystallization, which consists in continuously feeding such substance to and delivering it from a centrifugal drier; causing the treated material on leaving the rotor of such drier to travel through the air or surrounding medium free from. contact with any material support a. distance sutficient to effect complete traneous to the rotor that the solid particlesthrown off by said rotor will, during their unsupported travel through the surrounding medium and before reaching or making contact with any arresting surface, be deprived through evaporation, congelation, crystallization, or any or all of these, of practically all free moisture.

4. Apparatus for removing free moisture from substances in granular or divided form, comprising a centrifugal drier; and a bed or latform to receive the solid particles disc urged by said centrifugal drier, said bed or platformbeing of such dimensions and located at a distance from the dischar e zone of thefcentrifu al drier such that tl ie free moisture carried by the particles, d charged from its rotor shall be dissipated by evaporation, congelation, or both, during the movement of the particles through the air and prior to contact with the bed or platform.

5. An apparatus for elimination of free moisture from bodies in granular, crystalline, or divided form, comprising a centrifugal drier; a receiving bed or latform for the solid particles discharged 'rom the rotor of the drier after treatment therein; and

a i an encompassmg-wall-for said drier and bed or platform, the bed or platform and the wall being at such distance from and in such relation to the discharge outlet of the rotor of the centrifugal drier that the free moisture carried by the discharged particles shall be substantially dissipated by congelation, evaporation, or crystallization during the travel of the particles through the air, and

that said particles shall encounter the bed or platform or thev wall at an acute angle and with a gliding movement.-

6; Apparatus for removing free moisture from substances. in granular or divided form, comprising a rotor and means for imparting rapid rotation thereto"; and a bed or platform to receive the solid particles discharged by said rotor, said bed or platform the'movement of said particlesithrough the being of such dimensions and located at a air and prior to contact with the bed or distance from the'discharge zone of the roplatform. l0 tor such that the free moisture carried by In testimony whereof'we have signed our 5 the particles discharged from the rotor shall names to this specification.

be dissipated by evaporation, congelation, GUY H. ELMORE. crystallization, or-any or. all of these, during ROY C. COMLEY. 

